1. Field of the Invention
The present invention relates to an auto-stabilized high power electric power supply generator, especially but not exclusively for powering of processes involving a discharge into a rarefied gaseous atmosphere. The invention is advantageously applied to a furnace for the thermal or thermochemical treatment of metals by ionic bombardment.
2. Description of the Prior Art
It is known that furnaces of the aforesaid kind comprise an anode and a cathode serving as a support for pieces to be treated, connected to a power circuit with a high voltage electric current.
Therefore, according to a first embodiment there is applied between the cathode and anode a potential difference such that, following a transitional period, the process is maintained in the irregular discharge zone of the voltage intensity curve, incident to an electrical discharge in the gas contained in the furnace.
This embodiment makes it possible to obtain a significant dissipation of energy at the cathode and, consequently, cause rapid heating of the piece.
However, its principal drawback resides in the fact that being near the arcing region, there is frequently produced the beginnings of arcing which pose the risk of deteriorating the pieces notwithstanding the use of systems for arc rupture.
A second embodiment uses, instead of a continuous current, high voltage current pulses, the total energy of which has a predetermined value calculated in such a way that there cannot be produced any arc formation, even if the arc formation zone is attained on the voltage/intensity discharge curve.
Therefore, ions are essentially obtained with a high kinetic energy and in a very limited quantity, which makes it possible to increase the quality of the treatment and its homogeneity without involving an excessive temperature level.
However, a drawback of this process resides in that the treatment temperature is obtained only after a rather long period of time and, in addition, is unsuitable for high levels of power.